U.S. patent application number 12/328351 was filed with the patent office on 2010-06-10 for amphoteric dispersants and their use in inkjet inks.
Invention is credited to Robert Paul Held, Patrick F. McIntyre, C. Chad Roberts.
Application Number | 20100143590 12/328351 |
Document ID | / |
Family ID | 42231386 |
Filed Date | 2010-06-10 |
United States Patent
Application |
20100143590 |
Kind Code |
A1 |
Held; Robert Paul ; et
al. |
June 10, 2010 |
Amphoteric dispersants and their use in inkjet inks
Abstract
The present disclosure provides a black ink-jet ink, having a pH
greater than 7, comprising a first aqueous vehicle, a carbon black
pigment, and an amphoteric polymeric dispersant, wherein the
amphoteric polymeric dispersant is a block copolymer comprising an
A block and a B block, wherein the A block is a segment consisting
essentially of an amine monomer; and the B block is a segment
comprising an acidic monomer and at least one hydrophobic monomer;
wherein the dispersant is neutralized, and with the proviso that
the acid number is greater that the amine number, and the B block
does not contain an amine monomer. The disclosure further pertains
to an ink set comprising this black ink and at least a second ink
which contains a reactive species with appropriate cationic agent,
salt, or pH capable of destabilizing the carbon black dispersion.
Still further, the disclosure pertains to a method of printing
wherein the black ink and second ink are printed in an adjacent
relationship, thereby minimizing penetration, feathering and/or
bleed of the black pigment and improving print quality.
Inventors: |
Held; Robert Paul; (Newark,
DE) ; Roberts; C. Chad; (Wilmington, DE) ;
McIntyre; Patrick F.; (West Chester, PA) |
Correspondence
Address: |
E I DU PONT DE NEMOURS AND COMPANY;LEGAL PATENT RECORDS CENTER
BARLEY MILL PLAZA 25/1122B, 4417 LANCASTER PIKE
WILMINGTON
DE
19805
US
|
Family ID: |
42231386 |
Appl. No.: |
12/328351 |
Filed: |
December 4, 2008 |
Current U.S.
Class: |
427/256 ;
347/100; 524/548; 524/555 |
Current CPC
Class: |
C08L 53/00 20130101;
C08L 53/00 20130101; C08F 293/005 20130101; C09D 153/00 20130101;
C09D 11/324 20130101; C09D 11/326 20130101; C09D 153/00 20130101;
C08L 2666/02 20130101; C08L 2666/02 20130101; C09D 11/40
20130101 |
Class at
Publication: |
427/256 ;
524/555; 524/548; 347/100 |
International
Class: |
B05D 5/00 20060101
B05D005/00; C08L 53/00 20060101 C08L053/00; C08L 39/08 20060101
C08L039/08; G01D 11/00 20060101 G01D011/00 |
Claims
1. A black ink-jet ink, having a pH greater than 7, comprising a
first aqueous vehicle, a carbon black pigment, and an amphoteric
polymeric dispersant, wherein the amphoteric polymeric dispersant
is a block copolymer comprising an A block and a B block, wherein
the A block is a segment consisting essentially of an amine
monomer; and the B block is a segment comprising an acidic monomer
and at least one hydrophobic monomer; wherein the dispersant is
neutralized, and with the proviso that the acid number is greater
than the amine number, and the B block does not contain an amine
monomer.
2. The black ink-jet ink of claim 1 wherein the amine monomer is
selected from the group consisting essentially of
dimethylaminoethyl (meth)acrylate, diethylaminoethyl(meth)acrylate,
t-butylaminoethyl-(meth)acrylate, vinyl pyridine, 4-aminostyrene,
and 4-(N,N-dimethylamino)-styrene.
3. The black ink-jet ink of claim 1 wherein the acidic monomer is
methacrylic acid or acrylic acid.
4. The black ink-jet ink of claim 1 wherein the hydrophobic monomer
is selected from the group consisting essentially of benzyl
methacrylate, butyl(meth)acrylate, methyl methacrylate, butyl
methacrylate, ethylhexyl methacrylate, 2-phenylethyl methacrylate,
ethyl acrylate, hydroxyethyl acrylate, butyl acrylate, and
2-phenylethyl acrylate.
5. The black ink-jet ink of claim 1 wherein the block copolymer has
a number average molecular weight (Mn) of between about 3,000 and
about 16,000 Daultons.
6. The black ink-jet ink of claim 1 wherein the block copolymer has
an acid number of between about 30 and about 220 (mg KOH to
neutralize 1 gram of polymer solids).
7. The black ink-jet ink of claim 6 wherein the block copolymer has
an acid number of between about 30 and about 200 (mg KOH to
neutralize 1 gram of polymer solids).
8. The black ink-jet ink of claim 1 wherein the A block segment
comprises 2 to 8 units of an amine monomer.
9. The black ink-jet ink of claim 1 wherein the B block comprises
at least 6 units of acid monomer, and at least 16 units of at least
one hydrophobic monomer.
10. The black ink-jet ink of claim 1 wherein the acid groups on the
dispersant polymer are partially or completely neutralized with
base to the salt form.
11. The black ink-jet ink of claim 10 wherein the base is selected
from the group consisting essentially of alkali metal hydroxides,
alkali metal carbonate, alkali metal bicarbonate, organic amines,
organic alcohol amines, ammonium salts, and pyridine.
12. The black ink-jet ink of claim 1 wherein the amphoteric
polymeric dispersant has an amine number of about 10 to about 180
mg KOH/g solids.
13. The black ink-jet ink of claim 1 wherein the amphoteric
polymeric dispersant has a polydispersity of less than about 2.
14. The black ink-jet ink of claim 1 wherein the amphoteric
polymeric dispersant is present in the amount of about 0.3% to
about 5.0%, based on the total weight of the black ink.
15. An ink set comprising a first ink and a second ink wherein the
first ink is a black ink having a pH greater than 7, and comprises
a first aqueous vehicle, and a carbon black dispersion comprising a
carbon black pigment, and an amphoteric polymeric dispersant,
wherein the amphoteric polymeric dispersant is a block copolymer
comprising an A block and a B block, wherein the A block is a
segment consisting essentially of an amine monomer; and the B block
is a segment comprising an acidic monomer and at least one
hydrophobic monomer; wherein the dispersant is neutralized, and
with the proviso that the acid number is greater than the amine
number, and the B block does not contain an amine monomer; and the
second ink comprises a second aqueous vehicle and reactive species
that can destabilize the carbon black dispersion of said first
ink.
16. The ink set of any claim 15 wherein the second ink further
comprises a colorant.
17. The ink set of claim 16 wherein the colorant in the second ink
is a dye.
18. The ink set of claim 15 wherein the amine monomer is selected
from the group consisting essentially of dimethylaminoethyl
(meth)acrylate, diethylaminoethyl(meth)acrylate,
t-butylaminoethyl-(meth)acrylate, vinyl pyridine, 4-aminostyrene,
and 4-(N,N-dimethylamino)-styrene.
19. The ink set of claim 15 wherein the acidic monomer is
methacrylic acid or acrylic acid.
20. The ink set of claim 15 wherein the hydrophobic monomer is
selected from the group consisting essentially of benzyl
methacrylate, butyl(meth)acrylate, methyl methacrylate, butyl
methacrylate, ethylhexyl methacrylate, 2-phenylethyl methacrylate,
ethyl acrylate, hydroxyethyl acrylate, butyl acrylate, and
2-phenylethyl acrylate.
21. The ink set of claim 15 wherein the block copolymer has a
number average molecular weight (Mn) of between about 3,000 and
about 16,000 Daultons.
22. The ink set of claim 15 wherein the block copolymer has an acid
number of between about 50 and about 220 (mg KOH to neutralize 1
gram of polymer solids).
23. The ink set of claim 15 wherein the reactive species is a
cationic agent, salt, or pH.
24. The ink set of claim 15 wherein the reactive species is part of
the molecular structure of the colorant.
25. A method of ink jet printing onto a substrate comprising, in
any workable order, the steps of: (a) providing an ink jet printer
that is responsive to digital data signals; (b) loading the printer
with a substrate to be printed; (c) loading the printer with an ink
set comprising at least a first and second ink wherein said first
ink is a black ink having a pH greater than 7, and comprises a
first aqueous vehicle, and a carbon black dispersion comprising a
carbon black pigment, and an amphoteric polymeric dispersant,
wherein the amphoteric polymeric dispersant is a block copolymer
comprising an A block and a B block, wherein the A block is a
segment consisting essentially of an amine monomer; and the B block
is a segment comprising an acidic monomer and at least one
hydrophobic monomer; wherein the dispersant is neutralized, and
with the proviso that the acid number is greater than the amine
number, and the B block does not contain an amine monomer; and the
second ink comprises a second aqueous vehicle and reactive species
that can destabilize the carbon black dispersion of said first ink;
and (d) printing onto the substrate using the ink set, in response
to the digital data signals, such that one or more regions of the
substrate printed with said first ink are adjacent with said second
ink.
26. An ink jet printer comprising the black ink-jet ink of claim
1.
27. An ink jet printer comprising the ink set of claim 15.
28. The black ink-jet ink of claim 1 wherein the A block is a
segment consisting of an amine monomer.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from U.S. Provisional
Application Ser. No. 60/007,409 (filed Dec. 12, 2007), the
disclosure of which is incorporated by reference herein for all
purposes as if fully set forth.
BACKGROUND OF THE DISCLOSURE
[0002] The present disclosure relates to an aqueous inkjet ink
comprising carbon black pigment stabilized by a certain block
copolymer dispersant. The disclosure further relates to an ink set
comprising this ink and to a method of printing with the ink
set.
[0003] Inkjet printing is a non-impact printing process in which
droplets of ink are deposited on a substrate, such as paper, to
form the desired image. The droplets are ejected from a printhead
in response to electrical signals generated by a
microprocessor.
[0004] Most inkjet printers are equipped with an ink set comprising
two or more different inks and are able to print black text and
multicolor images. Typically, an ink set will comprise at least a
cyan, magenta and yellow colored ink and a black ink (CMYK ink
set).
[0005] For printing text, it is desirable for the black ink to have
high optical density. For this purpose, a pigment colorant is most
advantageous, especially a carbon black pigment. A pigment colorant
is not soluble in the ink vehicle and must be treated in order to
cause it to remain dispersed and jet properly.
[0006] To effect dispersion stability, pigments are commonly
treated with dispersants, and a wide variety of such materials have
been disclosed. Especially effective are block copolymer
dispersants which are described, for example, in U.S. Pat. Nos.
5,085,698, 5,519,085, 5,272,201, and 5,648,405. These patents
disclose several types of diblock and triblock acrylic copolymers
with amine and acidic monomers, such as N,N-dimethylaminoethyl
methacrylate (DMAEMA) and methacrylic acid (MAA) monomers,
incorporated in either the hydrophilic or hydrophobic block, but
there is no disclosure of a block copolymer having a separate amine
containing homo-block. Other copolymer dispersant examples include
benzylmethacrylate (BZMA)//methacrylic acid (MAA) 13//10 block
copolymer with number average molecular weight (Mn) of 2966
disclosed in U.S. Pat. No. 5,852,075 and benzylmethacrylate
(BZMA)//methacrylic acid (MAA) 13//3 block copolymer with number
average molecular weight (Mn) of 2522 disclosed in U.S. patent
publication US2005/0090599. Amphoteric (sometimes referred to as
polyampholyte) dispersants, i.e., dispersants containing moieties
capable of reacting with acidic and basic reagents, for improved
dispersion stability, have also been described. For example, U.S.
Pat. No. 5,648,405 discloses an amphoteric dispersant formed of
MAA/DMAEMA/BzMA random copolymer, but there is no disclosure of
amphoteric dispersants with block structures.
[0007] For CMYK ink sets comprising a pigment black ink, it is
known to print the black ink in an adjacent relationship with one
or more of the colored inks to improve the print quality of the
black ink when the one or more colored ink(s) are formulated with
an ingredient that destabilizes the black pigment dispersion for
improved black-to-color bleed control and thus improved print
quality. Such ink sets and printing method are disclosed for
example in U.S. Pat. Nos. 5,734,403 and 6,354,693, and in European
Patent Publication 1,125,994 A1.
[0008] Despite the successful inkjet inks and print methods
presently available, there is still a need for, and it is an
objective of this disclosure to provide, inks and methods having
even better print quality and jetting reliability.
SUMMARY OF THE DISCLOSURE
[0009] In a first aspect, the disclosure provides a black ink-jet
ink, with pH greater than 7, comprising a first aqueous vehicle, a
carbon black pigment, and an amphoteric polymeric dispersant,
wherein the amphoteric polymeric dispersant is a block copolymer
comprising an A block and a B block wherein the A block is a
segment consisting essentially of an amine monomer, more typically
an amine containing vinylic monomer, such as dimethylaminoethyl
methacrylate; and the B block is a segment comprising an acidic
monomer and at least one hydrophobic monomer, such as
benzylmethacrylate, butylmethacrylate, etc.; wherein the dispersant
is neutralized, and with the proviso that the acid number is
greater than the amine number, and the B block does not contain an
amine monomer.
[0010] In the first aspect, the block copolymer has a number
average molecular weight (Mn) of between about 2000 and about
16,000 Daultons, more typically between about 3,000 and about
12,000 Daultons, and an acid number of between about 25 and about
220 (mg KOH to neutralize 1 gram of polymer solids), more typically
between about 30 and about 200.
[0011] In the first aspect, the A block segment is 2 to 8 units of
an amine monomer, and the B block is a segment comprising at least
6 units of acid monomer, and at least 16 units of at least one
hydrophobic monomer.
[0012] In a second aspect, the disclosure provides an ink set
comprising a first ink and a second ink, wherein the first ink is a
black ink, with pH greater than 7, comprising a first aqueous
vehicle, and a carbon black dispersion comprising a carbon black
pigment, and an amphoteric polymeric dispersant; wherein the
amphoteric polymeric dispersant is a block copolymer comprising an
A block and a B block wherein the A block is a segment consisting
essentially of an amine monomer, such as dimethylaminoethyl
methacrylate; and the B block is a segment comprising an acidic
monomer and at least one hydrophobic monomer, such as
benzylmethacrylate, butylmethacrylate, etc.; wherein the dispersant
is neutralized, and with the proviso that the acid number is
greater than the amine number, and the B block does not contain an
amine monomer; and said second ink comprises a second aqueous
vehicle and reactive species with appropriate cationic agent, salt,
or pH that can destabilize the carbon black dispersion of said
first ink and typically the reactive species is structurally part
of a colorant.
[0013] In a third aspect, the disclosure provides a method of
inkjet printing on a substrate, comprising the steps of:
[0014] (a) providing an ink jet printer that prints in response to
digital data signals;
[0015] (b) loading the printer with a substrate to be printed;
[0016] (c) loading the printer with an ink jet ink set comprising a
first and second ink; and
[0017] (d) printing said first and second ink on the substrate, in
an abutting relationship to each other; wherein the first ink is a
black ink, with pH greater than 7, comprising a first aqueous
vehicle, and a carbon black dispersion comprising a carbon black
pigment, and an amphoteric polymeric dispersant; wherein the
amphoteric polymeric dispersant is a block copolymer comprising an
A block and a B block wherein the A block is a segment consisting
essentially of an amine monomer, such as dimethylaminoethyl
methacrylate; and the B block is a segment comprising an acidic
monomer and at least one hydrophobic monomer, such as
benzylmethacrylate, butylmethacrylate, etc.; wherein the dispersant
is neutralized, and with the proviso that the acid number is
greater than the amine number, and the B block does not contain an
amine monomer; and said second ink comprises a second aqueous
vehicle and reactive species that can destabilize the carbon black
dispersion of said first ink.
[0018] These and other features and advantages of the present
disclosure will be more readily understood by those of ordinary
skill in the art from a reading of the following detailed
description. It is to be appreciated that certain features of the
disclosure which are, for clarity, described above and below in the
context of separate embodiments, may also be provided in
combination in a single embodiment. Conversely, various features of
the disclosure that are, for brevity, described in the context of a
single embodiment, may also be provided separately or in any
subcombination. In addition, references in the singular may also
include the plural (for example, "a" and "an" may refer to one, or
one or more) unless the context specifically states otherwise.
Further, values stated in ranges include each and every value
within that range.
DETAILED DESCRIPTION OF THE DISCLOSURE
Black Ink
[0019] The black ink comprises a first aqueous vehicle, a carbon
black dispersion comprising a carbon black pigment and an
amphoteric polymeric dispersant. Optionally the black ink further
comprises other ingredients.
[0020] The ink vehicle is the liquid carrier (or medium) for the
colorant(s) and optional additives. The term "aqueous vehicle"
refers to a vehicle comprised of water or a mixture of water and
one or more organic, water-soluble vehicle components commonly
referred to as co-solvents or humectants. Sometimes in the art,
when a co-solvent can assist in the penetration and drying of an
ink on a printed substrate, it is referred to as a penetrant.
[0021] Examples of water-soluble organic solvents and humectants
include: alcohols, ketones, keto-alcohols, ethers and others, such
as thiodiglycol, sulfolane, 2-pyrrolidone,
1,3-dimethyl-2-imidazolidinone and caprolactam; glycols such as
ethylene glycol, diethylene glycol, triethylene glycol,
tetraethylene glycol, propylene glycol, dipropylene glycol,
tripropylene glycol, trimethylene glycol, butylene glycol and
hexylene glycol; addition polymers of oxyethylene or oxypropylene
such as polyethylene glycol, polypropylene glycol and the like;
triols such as glycerol and 1,2,6-hexanetriol; lower alkyl ethers
of polyhydric alcohols, such as ethylene glycol monomethyl ether,
ethylene glycol monoethyl ether, diethylene glycol monomethyl,
diethylene glycol monoethyl ether; lower dialkyl ethers of
polyhydric alcohols, such as diethylene glycol dimethyl or diethyl
ether; urea and substituted ureas.
[0022] Examples of co-solvents that commonly act as penetrants
include higher alkyl glycol ethers and/or an 1,2-alkanediols.
Glycol ethers include, for example, ethylene glycol monobutyl
ether, diethylene glycol mono-n-propyl ether, ethylene glycol
mono-iso-propyl ether, diethylene glycol mono-iso-propyl ether,
ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl
ether, diethylene glycol mono-n-butyl ether, triethylene glycol
mono-n-butyl ether, diethylene glycol mono-t-butyl ether,
1-methyl-1-methoxybutanol, propylene glycol mono-t-butyl ether,
propylene glycol mono-n-propyl ether, propylene glycol
mono-iso-propyl ether, propylene glycol mono-n-butyl ether,
dipropylene glycol mono-n-butyl ether, dipropylene glycol
mono-n-propyl ether, and dipropylene glycol mono-isopropyl ether.
The 1,2-alkanediol penetrants include linear, for example, 1,2-(C5
to C8) alkanediols and especially 1,2-pentanediol and
1,2-hexanediol.
[0023] An aqueous vehicle will typically contain about 50% to about
96% water with the balance (i.e., about 50% to about 4%) being the
water-soluble solvent/humectant.
[0024] Raw carbon black pigment is insoluble and non-dispersible in
the ink vehicle and must be treated in order to form a stable
dispersion. According to the present disclosure, the carbon black
pigment is stabilized in the aqueous vehicle by treatment with an
amphoteric polymeric dispersant which is a block copolymer
comprising an A block and a B block wherein the A block is a
segment consisting essentially of, more typically consisting only
of, an amine monomer, more typically an amine containing vinylic
monomer, such as dimethylaminoethyl(meth)acrylate,
diethylaminoethyl(meth)acrylate, t-butylaminoethyl(meth)acrylate,
vinyl pyridine, 4-aminostyrene, 4-(N,N-dimethylamino)styrene; and
the B block is a segment comprising an acidic monomer and at least
one hydrophobic monomer. Some suitable acidic monomers include
methacrylic acid and acrylic acid, and some suitable hydrophobic
monomers are selected from the group consisting essentially of
benzyl methacrylate, butyl(meth)acrylate, methyl methacrylate,
butyl methacrylate, ethylhexyl methacrylate, 2-phenylethyl
methacrylate, ethyl acrylate, hydroxyethyl acrylate, butyl
acrylate, and 2-phenylethyl acrylate.
[0025] The acid number of the amphoteric polymeric dispersant is
greater than the amine number. Further, the B block does not
contain an amine monomer. Typically, the A block segment is about 2
to about 8 units of an amine monomer, more typically about 3 to
about 6 units of an amine monomer. The B block is a segment
comprises at least about 6 units of acid monomer, more typically at
least about 7 to about 11 units of acid monomer, and at least about
16 units of at least one hydrophobic monomer, more typically at
least about 20 units of at least one hydrophobic monomer.
Typically, the block copolymer has a number average molecular
weight (Mn) of between about 2,000 and about 16,000 Daultons, more
typically between about 3,000 and about 12,000 Daultons, and an
acid number of between about 50 and about 220 (mg KOH to neutralize
1 gram of polymer solids), more typically between about 30 and
about 200. Typically, the amine number is about 10 to about 180 mg
KOH/g solids, more typically about 25 to about 100 mg KOH/g
solids.
[0026] Typically, the amphoteric polymer dispersant is an AB, ABA
or BAB block copolymer, although AB block copolymers with a
homo-block of amine monomer is generally preferred.
[0027] The weight ratio of pigment to dispersant (P/D) is typically
between about 0.5 and about 5. The acid groups on the dispersant
polymer will typically be partially or completely neutralized with
base to the salt form. Some examples of useful bases include alkali
metal hydroxides (lithium, sodium, and potassium hydroxide), alkali
metal carbonate and bicarbonate (sodium and potassium carbonate and
bicarbonate), organic amines (mono-, di-, tri-methylamine,
morpholine, N-methylmorpholine), organic alcohol amines
(N,N-dimethylethanolamine, N-methyl diethanolamine, mono-, di-,
tri-ethanolamine), ammonium salts (ammonium hydroxide, tetra-alkyl
ammonium hydroxide), and pyridine.
[0028] The amphoteric polymeric dispersant is present in the amount
of about 0.3% to about 5.0%, more typically about 1.0% to about
2.5%, based on the total weight of the black ink.
[0029] Sources of carbon black pigment are well known to those of
ordinary skill in the art. Likewise, methods of making block
copolymers are known and include, for example, those methods
described in U.S. Pat. Nos. 5,085,698 and 5,852,075, and U.S.
patent publication US2005/0090599.
[0030] Controlled polymerization techniques such as Group Transfer
Polymerization (GTP) or Reversible-Addition Fragmentation Transfer
(RAFT) polymerization are typical because polymers produced thereby
have precisely controlled molecular weight, block sizes and very
narrow molecular weight distributions. These polymers typically
have a polydispersity of less than about 2, generally in the range
of about 1.0 to about 1.4. Polydispersity is the polymer weight
average molecular weight (Mw) divided by its number average
molecular weight (Mn). The dispersant polymers may be synthesized
by established methods as described, for example, in U.S. Pat. Nos.
5,085,698 and 5,852,075 along with U.S. patent publication
US2005/0090599, the disclosures of which are incorporated herein by
reference.
[0031] To prepare the dispersion, the pigment and amphoteric
polymeric dispersant are premixed. Typically the mixing device is a
High Speed Disperser, which may be equipped with a Cowels type
blade. The premixed pigment and amphoteric polymeric dispersant are
then dispersed or deflocculated in a milling step. The premixture
includes an aqueous carrier medium (such as water and, optionally,
a water-miscible solvent) when the milling step involves a wet
milling operation. The milling may be accomplished in a 2-roll
mill, media mill, a horizontal mini mill, a ball mill, an attritor,
or by passing an aqueous premix through a plurality of nozzles
within a liquid jet interaction chamber at a liquid pressure of at
least 5,000 psi to produce a uniform dispersion of the pigment
particles in the aqueous carrier medium (microfluidizer).
Alternatively, the concentrates may be prepared by dry milling the
amphoteric polymeric dispersant and the pigment under pressure. The
media for the media mill is chosen from commonly available media,
including zirconia, YTZ.RTM. (Nikkato Corporation, Osaka, Japan),
and nylon. Typically the milled dispersion is filtered after the
milling step. These various dispersion processes are in a general
sense well-known in the art, as exemplified by U.S. Pat. Nos.
5,022,592, 5,026,427, 5,310,778, 5,891,231, 5,679,138, 5,976,232
and U.S. patent publication 2003/0089277. The pigment dispersion as
made is typically in a concentrated form (dispersion concentrate),
which is subsequently diluted with a suitable liquid containing the
desired additives to make the final ink.
[0032] The range of useful particle sizes after dispersion is
typically about 0.005 micron to about 15 micron. More typically,
the pigment particle size should range from about 0.005 to about 5
micron and, most typically, from about 0.005 to about 1 micron. The
average particle size as measured by dynamic light scattering is
less than about 500 nm, more typically less than about 300 nm.
[0033] The levels of pigment employed in formulated inks are those
levels needed to impart a desirable optical density to the printed
image. Typically, pigment levels are in the range of about 0.01 wt
% to about 10 wt %, and more typically from about 1 wt % to about 9
wt %.
[0034] Other ingredients, additives, may be formulated into the
inkjet ink, to the extent that such other ingredients do not
interfere with the stability and jettablity of the ink, which may
be readily determined by routine experimentation. Such other
ingredients are in a general sense well known in the art.
[0035] Commonly, surfactants are added to the ink to adjust surface
tension and wetting properties. Suitable surfactants include
ethoxylated acetylene diols (e.g. Surfynols.RTM. series from Air
Products), ethoxylated primary (e.g. Neodol.RTM. series from Shell)
and secondary (e.g. Tergitol.RTM. series from Union Carbide)
alcohols, sulfosuccinates (e.g. Aerosol.RTM. series from Cytec),
organosilicones (e.g. Silwet.RTM. series from Witco) and fluoro
surfactants (e.g. Zonyl.RTM. series from DuPont). Surfactants are
typically used in amounts up to about 5 wt % and more typically in
amounts of no more than 2 wt %. Optionally, defoamers may be used
to remove air entrapment that occurs during premixing and/or
milling steps.
[0036] Polymers may be included in the ink as an additive to
improve durability of printed image and/or enhance the printer
performance of the inks. These polymers may be added to the ink up
to about 10 wt %, with 5 wt % being typical depending on impact on
performance. Suitable polymers include acrylic copolymers, polymer
latexes from emulsion polymerization, and polyurethane dispersions.
As with the dispersants mentioned herein before, polymer additives
preferably originate from a controlled polymerization techniques
such as Group Transfer Polymerization (GTP) or Reversible-Addition
Fragmentation Transfer (RAFT) polymerization. Block copolymers are
particularly useful for improving durability of the printed image
while maintaining excellent print performance. Polymer additives
can include the free addition of the same polymer used as the
dispersant.
[0037] Biocides may be used to inhibit growth of
microorganisms.
[0038] Pigmented ink jet inks typically have a surface tension in
the range of about 20 mN.m.sup.-1 to about 70 mN.m.sup.-1 at
25.degree. C. Viscosity can be as high as 30 mPas at 25.degree. C.,
but is typically somewhat lower. The ink has physical properties
compatible with a wide range of ejecting conditions, materials
construction and the shape and size of the nozzle. The inks should
have excellent storage stability for long periods so as not clog to
a significant extent in an ink jet apparatus. Further, the ink
should not corrode parts of the ink jet printing device it comes in
contact with, and it should be essentially odorless and
non-toxic.
[0039] Although not restricted to any particular viscosity range or
printhead, the inks of the disclosure are particularly suited to
lower viscosity applications. Thus the viscosity (at 25.degree. C.)
of the inks of this disclosure may be less than about 7 mPas, or
less than about 5 mPas, and even, advantageously, less than about
3.5 mPas.
Method of Printing and Ink Sets:
[0040] Inkjet ink sets comprise at least two different inks which
are used in combination to create the desired image. A typical
printer will generally comprise at least four differently colored
inks such as a cyan, magenta, yellow and black (CMYK) ink. Ink sets
may further comprise one or more "gamut-expanding" inks, including
different colored inks such as an orange ink, a green ink, a violet
ink, a red ink and/or a blue ink, and combinations of full strength
and light strengths inks such as light cyan and light magenta. In
addition, ink sets may include one or more colorless inks which are
printed in combination with the colored inks to enhance properties
such as optical density, chroma, durability and/or gloss.
[0041] According to one embodiment of the disclosure, a method of
ink jet printing onto a substrate is provided comprising, in any
workable order, the steps of: [0042] (a) providing an ink jet
printer that is responsive to digital data signals; [0043] (b)
loading the printer with a substrate to be printed; [0044] (c)
loading the printer with an ink set comprising at least a first and
second ink wherein said first ink is a black ink having a pH
greater than 7, and comprises a first aqueous vehicle, and a carbon
black dispersion comprising a carbon black pigment, and an
amphoteric polymeric dispersant, wherein the amphoteric polymeric
dispersant is a block copolymer comprising an A block and a B
block, wherein the A block is a segment consisting essentially of
an amine monomer; and the B block is a segment comprising an acidic
monomer and at least one hydrophobic monomer; wherein the
dispersant is neutralized, and with the proviso that the acid
number is greater than the amine number, and the B block does not
contain an amine monomer; and the second ink comprises a second
aqueous vehicle and reactive species with appropriate cationic
agent, salt, or pH that can destabilize the carbon black dispersion
of said first ink; and [0045] (d) printing onto the substrate using
the ink set, in response to the digital data signals, such that one
or more regions of the substrate printed with said first ink are
adjacent with said second ink.
[0046] The second ink can be colored or colorless. In a typical
embodiment, the second ink is colored and most typically a cyan,
magenta or yellow ink in a multicolor ink set. Typically, a colored
second ink comprises a dye colorant which, by definition, is
soluble in the ink vehicle. The second vehicle may be the same or
different than the first vehicle and is subject to similar
compositional considerations as that herein before described for
the black ink.
[0047] The selection of colorant for the second ink is well
understood by one skilled in the art, and should be reactive with
the amine block of the defined dispersant. Some examples of useful
dyes include (cyan) Acid Blue 9 and Direct Blue 199; (magenta) Acid
Red 52, Reactive Red 180, Acid Red 37 and Reactive Red 23; and
(yellow) Direct Yellow 86, Direct Yellow 132 and Acid Yellow 23.
The preceding dyes are referred to by their "C.I." designation
established by Society Dyers and Colourists, Bradford, Yorkshire,
UK and published in The Color Index, Third Edition, 1971.
[0048] Some examples of useful pigments include Nipex.RTM. 180,
Nipex.RTM. 160, Nipex.RTM. 150 and Printex.RTM. 80 which are
available from Degussa which is part Evonik Industries AG located
in Essen, Germany. The following table summarizes the properties of
these carbon black pigments.
TABLE-US-00001 TABLE 1 Carbon Black Pigments Primary Particle Oil %
Type Size, nm Surface Area Absorption Volatile Nipex .RTM. 180 15
260 160 4.5 Nipex .RTM. 160 20 150 150 4.5 Nipex .RTM. 150 29 110
115 7 Printex .RTM. 80 16 220 100 1.2
[0049] Reactive species in the second ink may include acid moieties
such as sulfonic and carbonyl acid as part of the molecular
structure of dyes or surfaces of pigments. The mechanism of bleed
control results from the amine in the dispersant structure reacting
with the acidic component in the second ink.
[0050] The inks of the present disclosure can be printed with any
suitable inkjet printer, including printers equipped with piezo or
thermal print heads. Some examples of thermal ink jet print heads
are the Hewlett Packard Deskjet, and Canon iPIXMA iP4200, and some
examples of piezo print heads are Brother MFC3360C, and Epson
Stylus C120. Some suitable print heads are disclosed in U.S. Pat.
No. 6,161,918, U.S. Pat. No. 4,490,728, and U.S. Pat. No.
6,648,463, the disclosures of which are incorporated herein by
reference. The substrate can be any suitable substrate including
plain paper, such as common electrophotographic copier paper;
treated paper, such as photo-quality inkjet paper. The present
disclosure is particularly advantageous for printing on plain
paper.
[0051] The following examples illustrate the disclosure without,
however, being limited thereto.
EXAMPLES
[0052] In the following examples, unless otherwise stated, water
was deionized and ingredient amounts were in weight percent of the
total weight of ink.
Glossary:
TABLE-US-00002 [0053] Surfynol .RTM. 465 Surfactant from Air
Products (Allentown, PA USA). Proxel .TM. GXL Biocide from Avecia
(Wilmington, DE, USA). Glycereth-26 26 mole ethylene oxide adduct
of glycerin.
Polymeric Dispersants:
[0054] The dispersant polymers used to make the dispersions were
synthesized by established methods as described, for example, in
U.S. Pat. Nos. 5,085,698 and 5,852,075 along with U.S. patent
publication US2005/0090599, the disclosures of which are
incorporated by reference herein as if fully set forth.
[0055] It should be noted that, in referring to the polymer
compositions, a double slash indicates a separation between blocks
and a single slash indicates a random copolymer. Thus,
BzMA//MAA//BzMA 8//10//8 is an ABA triblock polymer with a first A
block that is on average 8 BzMA (Benzyl Methacrylate) units long, a
B block that is on average 10 MAA (Methacrylic Acid) units long,
and a final A block that is on average 8 BZMA units long.
[0056] Polymeric dispersants were routinely synthesized in dry THF
and converted to a solution in 2-pyrrolidone (2P) by distilling the
THF while replacing with 2P. In most cases, the dispersant was
pre-dissolved at approximately 20% polymer solids in water with the
aid of KOH to neutralized the acid moieties on the polymer.
[0057] The following synthetic examples were all based on group
transfer polymerization (GTP), although other types of
polymerization processes can be used to generate similar types of
polymers. In the case of the block polymers, the current block was
at least 95% converted before adding the mixture of monomers for
the next block. In all cases, the feed cycle strategy is described.
However, the synthesis was terminated when 99% of the monomer was
converted as detected by HPLC with mesitylene as an internal
standard. The molecular weight reported (unless otherwise noted) is
based on theoretical considerations. For the random linear
polymers, all monomer ratios reported as the mole ratios of the
monomer components, and represent the theoretical degree of
polymerization for each block or set of monomer units.
[0058] Standard laboratory techniques for handling water sensitive
chemicals were employed for the following examples. For example,
glassware was extensively dried before use, monomers were stored
over sieves, and cannulation procedures were used to keep material
dry.
[0059] Gel Permeation Chromatography or GPC was used to verify
predicted molecular weight and molecular weight distribution. The
GPC system was included a Waters 1515 Isocratic HPLC Pump, Waters
2414 Refractive Index Detector, 717 plus Waters Autosampler, Four
Styregel Columns (HR 0.5, HR 1, HR 2, and HR 4) in series in a
Waters Column Heater set to 40.degree. C. Samples were eluted with
Tetrahydrofuran (THF) at a flow rate of 1 mL/min. The samples were
analyzed using Breeze 3.30 Software with a calibration curve
developed from narrow molecular weight, polymethylmethacrylate
(PMMA) standards. Based on light scattering data from Polymer
Laboratories Ltd., the nominal, peak molecular weight for the PMMA
standards was as follows: 300000, 150000, 60000, 30000, 13000,
6000, 2000, and 1000.
[0060] The particle size was determined by dynamic light scattering
using a Microtrac Analyzer, Largo Fla. For many of the dispersion
steps, a Model 100 F or Y, Microfluidics System was used (Newton
Mass.).
TABLE-US-00003 Theor Theor Acid Amine Number Acid Number Amine mg
Value mg Value Dispersant Theor KOH/g mEq/g KOH/g mEq/g # Polymer
Structure Mn polymer polymer polymer polymer 1 MAA//BZMA/MAA
4//30/6 6226 99 1.77 0 0.00 2 DMAEMA//BZMA/MAA 4//30/11 6940 97
1.73 32 0.58 3 DMAEMA//BZMA/MAA 4//30/9 6768 83 1.48 33 0.59 4
DMAEMA//BZMA/MAA 4//30/7 6596 68 1.21 34 0.61 5 DMAEMA//BMA/MAA
4//30/6 5490 72 1.28 41 0.73 6 DMAEMA//BZMA/BMA/MAA 4//22.5/22.5/6
8385 47 0.83 27 0.48 7 DMAEMA//MMA/BMA/MAA 4//15/15/6 4860 81 1.44
46 0.82 8 MAA//BZMA/MAA/DMAEMA 4//30/6/5 7097 95 1.69 40 0.70 9
MAA//BZMA/DMAEMA 10//30/5 7011 88 1.57 40 0.71 10 DMAEMA//BZMA/MAA
8//30/9 7568 89 1.59 59 1.06
Dispersant 1: 4MAA//30BzMA/6MAA
[0061] A 3-liter round bottom flask was dried with a heat gun under
nitrogen purge and equipped with a mechanical stirrer,
thermocouple, N.sub.2 inlet, drying tube outlet, and addition
funnels. Tetrahydrofuran (THF), 426.4 g, was cannulated to the
flask. Initiator (1,1-bis(trimethylsilyloxy)-2-methyl propene, 18.4
g (0.0793 moles)) was injected followed by catalyst (tetrabutyl
ammonium m-chlorobenzoate, 0.5 ml of a 1.0 M solution in
acetonitrile). Catalyst solution (tetrabutyl ammonium
m-chlorobenzoate, 0.4 ml of a 1.0 M solution in acetonitrile and
THF, 5 g) was syringe pumped during both monomer feeds. Monomer
feed I (trimethylsilyl methacrylate, 50.5 g (0.3196 mol)) was added
over 15 minutes. After 1 hr hold, HPLC indicated greater than 98%
conversion, and then, monomer feed II (trimethylsilyl methacrylate,
75.1 g (0.4753 mol) and benzyl methacrylate, 416.4 g (2.3659 mol))
was added over 60 minutes while the reaction exothermed to
51.degree. C.
[0062] The conversion by HPLC was greater than 99%, 1 hr after the
feed was completed. 73 g of methanol were added, and then the THF
and other volatile by-products were distillated by slowly heating
to 120.degree. C. while 2P was added. The final polymer solution
was 48.9% solids with a measured acid value of 1.68
(milliequivalents/gram of polymer solids) based on total solids.
The molecular weight of this polymer as measured by GPC was Mn
6484, Mw 7511, and P: D of 1.16.
Dispersant 2: 4DMAEMA//30BzMA/11MAA
[0063] A 3-liter round bottom flask was dried with a heat gun under
nitrogen purge and equipped with a mechanical stirrer,
thermocouple, N2 inlet, drying tube outlet, and addition funnels.
Tetrahydrofuran (THF), 426.4 g, was cannulated to the flask.
Initiator (dimethyl ketene methyl trimethylsilyl acetal), 16.8 g
(0.0966 moles)) was injected followed by catalyst (tetrabutyl
ammonium m-chlorobenzoate, 0.4 ml of a 1.0 M solution in
acetonitrile). Catalyst solution (tetrabutyl ammonium
m-chlorobenzoate, 0.3 ml of a 1.0 M solution in acetonitrile and
THF, 10 g) was syringe pumped during both monomer feeds. Monomer
feed I (N,N-dimethylaminoethyl methacrylate, 61.3 g (0.3904 mol))
was added over 15 minutes. After a 45 min. hold, HPLC indicated
greater than 99% conversion, and then, monomer feed II
(trimethylsilyl methacrylate, 168.9 g (1.0690 mol) and benzyl
methacrylate, 509.6 g (2.8955 mol)) was added over 60 minutes while
the reaction exothermed to 51.degree. C.
[0064] The conversion by HPLC was greater than 97%, 1.5 hr after
the feed was completed. 99 g of methanol were added, and then the
THF and other volatile by-products were distillated by slowly
heating to 120.degree. C. while 2P was added. The final polymer
solution was 45.2% solids with a measured acid value of 1.64
(milliequivalents/gram of polymer solids) based on total solids.
The molecular weight of this polymer as measured by GPC was Mn
9938, Mw 12912, and P: D of 1.30.
Dispersant 3: 4DMAEMA//30BzMA/9MAA
[0065] A 3-liter round bottom flask was dried with a heat gun under
nitrogen purge and equipped with a mechanical stirrer,
thermocouple, N2 inlet, drying tube outlet, and addition funnels.
Tetrahydrofuran (THF), 511.6 g, was cannulated to the flask.
Initiator (1,1-bis(trimethylsilyloxy)-2-methyl propene), 18.5 g
(0.1063 moles)) was injected followed by catalyst (tetrabutyl
ammonium m-chlorobenzoate, 0.5 ml of a 1.0 M solution in
acetonitrile). Catalyst solution (tetrabutyl ammonium
m-chlorobenzoate, 0.4 ml of a 1.0 M solution in acetonitrile and
THF, 10 g) was syringe pumped during both monomer feeds. Monomer
feed I (N,N-dimethyl aminoethyl methacrylate, 66.9 g (0.4261 mol))
was added over 15 minutes. After a 15 min. hold, HPLC indicated
greater than 99% conversion, and then, monomer feed II
(trimethylsilyl methacrylate, 149.6 g (0.9468 mol) and benzyl
methacrylate, 555.3 g (3.1551 mol)) was added over 60 minutes while
the reaction exothermed to 52.degree. C.
[0066] The conversion by HPLC was greater than 99%, 2 hr after the
feed was completed. 95 g of methanol were added, and then the THF
and other volatile by-products were distillated by slowly heating
to 120.degree. C. while 2P was added. The final polymer solution
was 44.7% solids with a measured acid value of 1.40
(milliequivalents/gram of polymer solids) based on total solids.
The molecular weight of this polymer as measured by GPC was Mn
8616, Mw 10746, and P: D of 1.25.
Dispersant 4: 4DMAEMA//30BzMA/7MAA
[0067] A 3-liter round bottom flask was dried with a heat gun under
nitrogen purge and equipped with a mechanical stirrer,
thermocouple, N2 inlet, drying tube outlet, and addition funnels.
Tetrahydrofuran (THF), 497.6 g, was cannulated to the flask.
Initiator (dimethyl ketene methyl trimethylsilyl acetal, 21.8 g
(0.1253 moles)) was injected followed by catalyst (tetrabutyl
ammonium m-chlorobenzoate, 0.6 ml of a 1.0 M solution in
acetonitrile). Catalyst solution (tetrabutyl ammonium
m-chlorobenzoate, 0.4 ml of a 1.0 M solution in acetonitrile and
THF, 10 g) was syringe pumped during both monomer feeds. Monomer
feed I (N,N-dimethylaminoethyl methacrylate, 77.3 g (0.4924 mol))
was added over 15 minutes. After a 15 min. hold, HPLC indicated
greater than 98% conversion, and then, monomer feed II
(trimethylsilyl methacrylate, 136.0 g (0.8608 mol) and benzyl
methacrylate, 647.5 g (3.6376 mol)) was added over 60 minutes while
the reaction exothermed to 53.degree. C.
[0068] The conversion by HPLC was greater than 99%, 1 hr after the
feed was completed. 96 g of methanol were added, and then the THF
and other volatile by-products were distillated by slowly heating
to 120.degree. C. while 2P was added. The final polymer solution
was 50.1% solids with a measured acid value of 1.10
(milliequivalents/gram of polymer solids) based on total solids.
The molecular weight of this polymer as measured by GPC was Mn
7464, Mw 9221, and P: D of 1.24.
Dispersant 5: 4DMAEMA//30BzMA/6MAA
[0069] A 3-liter round bottom flask was dried with a heat gun under
nitrogen purge and equipped with a mechanical stirrer,
thermocouple, N2 inlet, drying tube outlet, and addition funnels.
Tetrahydrofuran (THF), 424.7 g, was cannulated to the flask.
Initiator (dimethyl ketene methyl trimethylsilyl acetal, 18.3 g
(0.1052 moles)) was injected followed by catalyst (tetrabutyl
ammonium m-chlorobenzoate, 0.5 ml of a 1.0 M solution in
acetonitrile). Catalyst solution (tetrabutyl ammonium
m-chlorobenzoate, 0.4 ml of a 1.0 M solution in acetonitrile and
THF, 10 g) was syringe pumped during both monomer feeds. Monomer
feed I (N,N-dimethylaminoethyl methacrylate, 66.6 g (0.4242 mol))
was added over 15 minutes. After a 15 min. hold, HPLC indicated
greater than 99% conversion, and then, monomer feed II
(trimethylsilyl methacrylate, 100.2 g (0.6342 mol) and benzyl
methacrylate, 555.3 g (3.1551 mol)) was added over 60 minutes while
the reaction exothermed to 57.degree. C.
[0070] The conversion by HPLC was greater than 99%, 45 minutes
after the feed was completed. 76 g of methanol were added, and then
the THF and other volatile by-products were distillated by slowly
heating to 120.degree. C. while 2P was added. The final polymer
solution was 49.5% solids with a measured acid value of 0.98
(milliequivalents/gram of polymer solids) based on total solids.
The molecular weight of this polymer as measured by GPC was Mn
8336, Mw 11125, and P: D of 1.34.
Dispersant 6: 4DMAEMA//22.5BzMA/22.5BMA/6MAA
[0071] A 3-liter round bottom flask was dried with a heat gun under
nitrogen purge and equipped with a mechanical stirrer,
thermocouple, N2 inlet, drying tube outlet, and addition funnels.
Tetrahydrofuran (THF), 560.6 g, was cannulated to the flask.
Initiator (dimethyl ketene methyl trimethylsilyl acetal, 14.8 g
(0.0851 moles)) was injected followed by catalyst (tetrabutyl
ammonium m-chlorobenzoate, 0.4 ml of a 1.0 M solution in
acetonitrile). Catalyst solution (tetrabutyl ammonium
m-chlorobenzoate, 0.3 ml of a 1.0 M solution in acetonitrile and
THF, 10 g) was syringe pumped during both monomer feeds. Monomer
feed I (N,N-dimethylaminoethyl methacrylate, 80.4 g (0.4242 mol))
was added over 15 minutes. After 20 minute hold, HPLC indicated
greater than 99% conversion, and then, monomer feed II
(trimethylsilyl methacrylate, 80.4 g (0.5089 mol), butyl
methacrylate, 268.9 g (1.8937 mol) and benzyl methacrylate, 333.2 g
(1.8932 mol)) was added over 60 minutes while the reaction
exothermed to 65.degree. C.
[0072] The conversion by HPLC was greater than 99%, 1.5 hr after
the feed was completed. 59.2 g of methanol were added, and then the
THF and other volatile by-products were distillated by slowly
heating to 120.degree. C. while 2P was added. The final polymer
solution was 45.8% solids with a measured acid value of 0.79
(milliequivalents/gram of polymer solids) based on total solids.
The molecular weight of this polymer as measured by GPC was Mn
10763, Mw 13356, and P: D of 1.24.
Dispersant 7: 4DMAEMA//15MMA/15BMA/6MAA
[0073] A 3-liter round bottom flask was dried with a heat gun under
nitrogen purge and equipped with a mechanical stirrer,
thermocouple, N2 inlet, drying tube outlet, and addition funnels.
Tetrahydrofuran (THF), 565.4 g, was cannulated to the flask.
Initiator (dimethyl ketene methyl trimethylsilyl acetal, 15.3 g
(0.0879 moles)) was injected followed by catalyst (tetrabutyl
ammonium m-chlorobenzoate, 0.4 ml of a 1.0 M solution in
acetonitrile). Catalyst solution (tetrabutyl ammonium
m-chlorobenzoate, 0.3 ml of a 1.0 M solution in acetonitrile and
THF, 10 g) was syringe pumped during both monomer feeds. Monomer
feed I (N,N-dimethylaminoethyl methacrylate, 55.2 g (0.3516 mol))
was added over 15 minutes. After a 10 minute hold, HPLC indicated
greater than 99% conversion, and then, monomer feed II
(trimethylsilyl methacrylate, 83.2 g (0.5266 mol), butyl
methacrylate, 280.1 g (1.9725 mol) and benzyl methacrylate, 346.9 g
(1.9710 mol)) was added over 60 minutes while the reaction
exothermed to 64.degree. C.
[0074] The conversion by HPLC was greater than 99%, 1 hr after the
feed was completed. 62.3 g of methanol were added, and then the THF
and other volatile by-products were distillated by slowly heating
to 120.degree. C. while 2P was added. The final polymer solution
was 49.6% solids with a measured acid value of 0.75
(milliequivalents/gram of polymer solids) based on total solids.
The molecular weight of this polymer as measured by GPC was Mn
11813, Mw 14080, and P: D of 1.19.
Dispersant 8: 4MAA//30BzMA/6MAA/5DMAEMA
[0075] A 5-liter round bottom flask was dried with a heat gun under
nitrogen purge and equipped with a mechanical stirrer,
thermocouple, N2 inlet, drying tube outlet, and addition funnels.
Tetrahydrofuran (THF), 1009.0 g, was cannulated to the flask.
Initiator (1,1-bis(trimethylsilyloxy)-2-methyl propene, 35.0 g
(0.1509 moles)) was injected followed by catalyst (tetrabutyl
ammonium m-chlorobenzoate, 0.6 ml of a 1.0 M solution in
acetonitrile). Catalyst solution (tetrabutyl ammonium
m-chlorobenzoate, 0.6 ml of a 1.0 M solution in acetonitrile and
THF, 11 g) was syringe pumped during both monomer feeds. Monomer
feed I (trimethylsilyl methacrylate, 95.6 g (0.6051 mol)) was added
over 15 minutes. After a 50 minute hold, HPLC indicated greater
than 98% conversion, and then, monomer feed II (trimethylsilyl
methacrylate, 144.5 g (0.9146 mol), benzyl methacrylate, 796.7 g
(4.5267 mol) and N,N-dimethylaminoethyl methacrylate, 118.6 g
(0.7554 mol)) was added over 60 minutes while the reaction
exothermed to 64.degree. C.
[0076] The conversion by HPLC was greater than 99%, 1.5 hr after
the feed was completed. 110.8 g of methanol were added, and then
the THF and other volatile by-products were distillated by slowly
heating to 120.degree. C. while 2P was added. The final polymer
solution was 43.9% solids with a measured acid value of 1.58
(milliequivalents/gram of polymer solids) based on total solids.
The molecular weight of this polymer as measured by GPC was Mn
7939, Mw 8754, and P: D of 1.10.
Dispersant 9: 10MAA//30BzMA/5DMAEMA
[0077] A 3-liter round bottom flask was dried with a heat gun under
nitrogen purge and equipped with a mechanical stirrer,
thermocouple, N2 inlet, drying tube outlet, and addition funnels.
Tetrahydrofuran (THF), 588.9 g, was cannulated to the flask.
Initiator (1,1-bis(trimethylsilyloxy)-2-methyl propene, 16.9 g
(0.0728 moles)) was injected followed by catalyst (tetrabutyl
ammonium m-chlorobenzoate, 0.4 ml of a 1.0 M solution in
acetonitrile). Catalyst solution (tetrabutyl ammonium
m-chlorobenzoate, 0.3 ml of a 1.0 M solution in acetonitrile and
THF, 5 g) was syringe pumped during both monomer feeds. Monomer
feed I (trimethylsilyl methacrylate, 114.2 g (0.7228 mol)) was
added over 15 minutes. After a 60 minute hold, HPLC indicated
greater than 97% conversion, and then, monomer feed II (benzyl
methacrylate, 382.1 g (2.1710 mol) and N,N-dimethylaminoethyl
methacrylate, 68.6 g (0.4369 mol)) was added over 60 minutes while
the reaction exothermed to 51.degree. C.
[0078] The conversion by HPLC was greater than 99% 1 hr after the
feed was complete. 118 g of methanol were added, and then the THF
and other volatile by-products were distillated by slowly heating
to 120.degree. C. while 2P was added. The final polymer solution
was 45.7% solids with a measured acid value of 1.56
(milliequivalents/gram of polymer solids) based on total solids.
The molecular weight of this polymer as measured by GPC was Mn
7019, Mw 8262, and P: D of 1.18.
Dispersant 10: 8DMAEMA//30BzMA/9MAA
[0079] A 3-liter round bottom flask was dried with a heat gun under
nitrogen purge and equipped with a mechanical stirrer,
thermocouple, N2 inlet, drying tube outlet, and addition funnels.
Tetrahydrofuran (THF), 571.1 g, was cannulated to the flask.
Initiator (1,1-bis(trimethylsilyloxy)-2-methyl propene, 24.4 g
(0.1052 moles)) was injected followed by catalyst (tetrabutyl
ammonium m-chlorobenzoate, 0.6 ml of a 1.0 M solution in
acetonitrile). Catalyst solution (tetrabutyl ammonium
m-chlorobenzoate, 0.5 ml of a 1.0 M solution in acetonitrile and
THF, 10 g) was syringe pumped during both monomer feeds. Monomer
feed I ((benzyl methacrylate, 558.5 g (3.1733 mol) and
trimethylsilyl methacrylate, 150.4 g (0.9519 mol)) was added over
60 minutes while the reaction exothermed to 68.degree. C. After a
60 minute hold, HPLC indicated greater than 99% conversion, and
then, monomer feed II (N,N-dimethylaminoethyl methacrylate, 133.2 g
(0.8484 mol)) was added over 15 minutes.
[0080] The conversion by HPLC was greater than 99%, 2 hr after the
feed was completed. 68 g of methanol were added, and then the THF
and other volatile by-products were distillated by slowly heating
to 120.degree. C. while 2P was added. The final polymer solution
was 46.5% solids with a measured acid value of 1.49
(milliequivalents/gram of polymer solids) based on total
solids.
Dispersion 1: Minimill Process, (M.M.):
[0081] Dispersion 1 was prepared using an Eiger Minimill media
milling process described below.
[0082] A 900 gram dispersion sample was prepared by adding the
following ingredients, in order, into a 1 Liter stainless steel
pot. Each ingredient was added slowly with mixing using a High
Speed Disperser equipped with a 60 mm Cowels type blade and
operated at 1000 rpm. The pigment loading in the premix stage was
25%.
TABLE-US-00004 Ingredients Amount (g) Deionized water 123.6
(MAA//BzMA/MAA, 4//30/6) 146.4 Nipex .RTM. carbon black pigment
90.0
[0083] After completing the pigment loading, the High Speed
Disperser speed was increased to 3000 rpm and the ingredients were
premixed for 2 hours.
[0084] Additional deionized water was then added to reduce pigment
level to 20% prior to milling.
TABLE-US-00005 Ingredients Amount (g) Deionized water 90.0
[0085] Next, the dispersion was processed on the Eiger Minimill
using a recirculation process at a flow-rate of 350 grams per
minute for 4 hours. After completion of milling process, the final
DI Water letdown was added to achieve the targeted 10% pigment
loading in the final dispersion.
TABLE-US-00006 Ingredients Amount (g) Deionized water 450.0
[0086] The final dispersion had a total batch size of approximately
900 grams. This dispersion was filtered through a 3.0 micron
Chipwich filter available from Pall Trincor of East Falls, N.Y. and
collected in a 1000 ml polyethylene container. Samples of the
dispersion were tested for pH, viscosity and particle size (D50 and
D95) which are reported in the Table 2 below.
[0087] Dispersions 2-3, 9-12, and 16-21 were prepared using the
above described Eiger Minimill media milling process using the
dispersants, pigments, % pigment loading and P/D identified in
Table 2 below.
Dispersion 4: Microfluidizer Process, (MF.)
[0088] Dispersion 4 was prepared using the Microfluidizer milling
process outlined below:
[0089] A 900 gram dispersion sample was prepared by adding the
following ingredients, in order, into a 1 Liter stainless steel
pot. Each ingredient was added slowly with mixing using a High
Speed Disperser, equipped with a 60 mm Cowels type blade, and
operated at 1000 rpm. The targeted pigment loading in the premix
stage was 23%.
TABLE-US-00007 Ingredients Amount (g) Deionized Water 139.7
(DMAEMA//BzMA/MAA, 4//30/6) 161.7 Nipex .RTM. carbon black pigment
90.0
[0090] After completing the pigment loading, the High Speed
Disperser speed was increased to 3500 rpm and the ingredients were
premixed for 2 hours.
[0091] Next, additional DI water was added to reduce pigment
loading to 15.0% which is the level used during milling.
TABLE-US-00008 Ingredients Amount (g) Deionized Water 208.7
[0092] The dispersion was milled for 12 passes at a flow rate of
350 ml/min and 15,000 psi through the Microfluidizer, that is a
labscale model M-110Y High Pressure Pneumatic Microfluidizer, with
a Z-Chamber available from Microfluidics of Newton, Mass.
Additional Deionized water was added to further reduce the pigment
loading to the targeted level of 10.0% pigment.
TABLE-US-00009 Ingredients Amount (g) Deionized Water 300
[0093] The dispersion was filtered through a 3.0 micron Chipwich
filter and filled into a 1000 ml polyethylene container. The
dispersion was tested for pH, viscosity, particle size (D50 and
D95) which are reported in the Table 2 below.
[0094] Dispersions 5-8, 14, 15 and 22 were prepared using the above
described Microfluidizer milling process using the dispersants,
pigments, % pigment loading and P/D identified in Table 2
below.
TABLE-US-00010 TABLE 2 Viscosity Disp. Dispersant Composition
Pigment % Pig P/D pH.sup.1 (cps).sup.2 D50.sup.3 D95.sup.3 Process
1 MAA//BzMA/MAA 4//30/6 Nipex .RTM. 180 9.88 2.50 8.95 3.31 101 168
M.M 2 MAA//BzMA/MAA 4//30/6 Nipex .RTM. 180 9.95 3.00 8.10 3.10 104
183 M.M 3 MAA//BzMA/MAA 4//30/6 Nipex .RTM. 180 10.02 3.50 8.00
3.10 105 192 M.M 4 DMAEMA//BMA/MAA 4//30/6 Nipex .RTM. 180 11.70
2.00 9.98 3.78 117 187 M.F. 5 DMAEMA//BMA/MAA 4//30/6 Nipex .RTM.
180 11.41 2.50 9.83 3.27 112 166 M.F. 6 DMAEMA//BzMA/MAA 4//30/7
Nipex .RTM. 150 10.75 2.00 9.30 3.10 160 270 M.F. 7
DMAEMA//BzMA/MAA 4//30/9 Nipex .RTM. 160 10.05 2.50 9.97 2.48 127
212 M.F. 8 DMAEMA//BzMA/MAA 4//30/9 Nipex .RTM. 160 9.92 3.00 9.89
2.35 126 192 M.F. 9 DMAEMA//BzMA/MAA 4//30/11 Nipex .RTM. 180 10.01
2.50 8.93 3.40 92 149 M.M 10 DMAEMA//BzMA/MAA 4//30/11 Nipex .RTM.
160 9.73 2.50 8.80 2.60 95 163 M.M 11 DMAEMA//BzMA/MAA 4//30/11
Nipex .RTM. 160 9.81 3.00 8.80 2.70 96 176 M.M 12 DMAEMA//BzMA/MAA
4//30/11 Printex .RTM. 80 9.76 2.50 9.40 2.60 86 165 M.M 13
DMAEMA//BzMA/MAA// 4//30/11//4 Nipex .RTM. 150 9.94 2.50 9.09 2.27
171 243 M.F. DMAEMA 14 DMAEMA//BzA/BMA/MAA 4//22.5/22.5/6 Nipex
.RTM. 150 11.21 2.00 9.06 3.00 171 273 M.F. 15 DMAEMA//BzA/BMA/MAA
4//22.5/22.5/6 Nipex .RTM. 150 10.69 2.50 9.29 2.58 181 287 M.F. 16
MAA//BzMA/MAA/DMAEMA 4//30/6/5 Nipex .RTM. 180 9.97 3.00 8.40 3.70
96 203 M.M 17 MAA//BzMA/MAA/DMAEMA 4//30/6/5 Nipex .RTM. 180 9.93
3.50 8.10 5.20 120 210 M.M 18 MAA//BzMA/MAA/DMAEMA 4//30/6/5 Nipex
.RTM. 180 15.10 2.00 8.88 21.20 98 168 M.M 19 MAA//BzMA/MAA/DMAEMA
4//30/6/5 Nipex .RTM. 180 14.99 2.50 8.40 65.00 105 191 M.M 20
MAA//BzMA/DMAEMA 10//30/5 Nipex .RTM. 180 9.07 2.00 7.90 4.00 91
138 M.M 21 MAA//BzMA/DMAEMA 10//30/5 Nipex .RTM. 180 9.09 2.50 7.88
4.90 112 200 M.M 22 DMAEMA//BzMA/MAA 8//30/9 Nipex .RTM. 180 10.04
2.50 9.89 2.80 87 139 M.F. .sup.1pH was measured using a model
511201 pH meter available from Beckman Coulter, Inc. of Fullerton,
CA. .sup.2Viscosity was measured using a model LVDV-II + Pro
Brookfield Viscometer available from Brookfield Engineering
Laboratories, Inc. of Middleboro, MA using a 00 Spindle and UL1
adapter. .sup.3Particle size measurements were made using a Model
NAS 35 Nanotrac Auto Sampler available from Microtrac Inc. of
Largo, FL.
Ink Preparation:
[0095] Inks were prepared by stirring together the pigment
dispersion and other ink ingredients according to the same general
formulation summarized in the following table. The dispersion was
added in an amount that provided 4% pigment solids in the final
ink.
TABLE-US-00011 Ingredient Weight % Dispersion (as wt % pigment) 4
Diethyleneglycol 3.6 Glycerol 3.4 Trimethylolpropane 3 Glycereth-26
2 Surfynol .RTM. 465 0.5 Proxel .TM. GXL 0.2 Water (to 100%)
Balance
Print Testing and Evaluation:
[0096] The black inks were printed with a Canon iPIXMA iP4200
(settings: plain media; normal print quality;). Standard cyan,
magenta and yellow dye inks designated for that printer were
used.
[0097] Line thickness patterns were printed with black line
thickness of about 300-420 micrometers printed next to color inks.
The reported values in the table of results with the black line on
paper is shown as K/W, with the black line next to yellow ink is
shown as K/Y and the black line next to two color red ink (yellow
plus magenta inks) is shown as K/R. In the table of results the top
and bottom black line edge Delta standard deviation for the three
images are shown as K/W, K/Y and K/R, respectively. The lower the
values, the better the intercolor bleed. The K/W values refer to
feathering which is a different phenomena from inter color
bleed.
[0098] The measurements of the black line printed images were done
with a device called "ImageXpert" manufactured by Imagexpert, Inc.,
Nashua, N.H. 03063.
Results:
[0099] The print test results for each ink are summarized in the
Table 3.
TABLE-US-00012 TABLE 3 Print Test Results Top & Bottom Line
Thickness Edge Delta (microns) Std Dev (microns) Polymer Structure
P/D Pigment K/W K/Y K/R K/W K/Y K/R Control 1 MAA/BZMA/MAA 4//30/6
2.5 Nipex 180 424 448 461 11 47 54 Control 2 MAA/BZMA/MAA 4//30/6
3.0 Nipex 180 458 605 476 10 51 55 Control 3 MAA/BZMA/MAA 4//30/6
3.5 Nipex 180 415 575 510 8 65 54 Ex 1 DMAEMA//BZMA/MAA 4//30/11
2.5 Nipex 180 455 458 466 19 19 22 Ex 2 DMAEMA//BZMA/MAA 4//30/11
2.5 Nipex 160 467 474 458 22 23 23 Ex 3 DMAEMA//BZMA/MAA 4//30/11
3.0 Nipex 160 472 482 469 23 22 27 Ex 4 DMAEMA//BZMA/MAA 4//30/11
2.5 Printex 80 475 475 455 25 24 25 Ex 5 DMAEMA//BZMA/MAA 4//30/9
2.5 Nipex 150 468 453 463 21 19.5 23 Ex 6 DMAEMA//BZMA/MAA 4//30/9
2.5 Nipex 160 469 471 445 22 24 20 Ex 7 DMAEMA//BZMA/MAA 4//30/9
3.0 Nipex 160 459 458 469 23 22 27 Ex 8 DMAEMA//BZMA/MAA 4//30/7
2.0 Nipex 150 425 435 424 8.5 13 12.5 Ex 9 DMAEMA//BMA/MAA 4//30/6
2.5 Nipex 180 339 330 336 6 8 11 Ex 10 DMAEMA//BMA/MAA 4//30/6 3.0
Nipex 180 335 336 339 6 11 13 Ex 11 DMAEMA//BZMA/BMA/MAA
4//22.5/22.5/6 2.0 Nipex 150 320 318 325 7 8 10 Ex 12
DMAEMA//BZMA/BMA/MAA 4//22.5/22.5/6 2.5 Nipex 150 317 320 325 6 8
10 Ex 13 DMAEMA//BzMA/MAA 8//30/9 2.5 Nipex 180 458 465 461 21 23
23 Comp Ex 1 MAA//BZMA/MAA/DMAEMA 4//30/6/5 3.0 Nipex 180 440 479
487 17 40 34 Comp Ex 2 MAA//BZMA/MAA/DMAEMA 4//30/6/5 3.5 Nipex 180
422 453 454 15 31 29 Comp Ex 3 MAA//BZMA/MAA/DMAEMA 4//30/6/5 2.0
Nipex 180 441 474 494 16 31 37 Comp Ex 4 MAA//BZMA/MAA/DMAEMA
4//30/6/5 2.5 Nipex 180 421 469 459 9 50 46 Comp Ex 5
MAA//BZMA/DMAEMA 10//30/5 2.0 Nipex 160 385 531 521 9.5 63 56 Comp
Ex 6 MAA//BZMA/DMAEMA 10//30/5 2.5 Nipex 160 442 530 456 7.5 60
44
[0100] The table of print test results shows the polymer using no
amine containing monomer in the structure (Control 1, 2 and 3) had
the poorest standard deviation for the intercolor bleed, as
indicated by the high K/Y and K/R values of top and bottom edge
delta standard deviation that are 47-65 microns.
[0101] If the amine monomer is in the structure or block where it
is incorporated into the hydrophobic and/or acid containing block,
e.g. Comp Ex 1-6, the intercolor bleed has poorer values of top and
bottom edge delta standard deviation shown as 31-63 microns,
compared to the polymer structure with the amine in a distinct
block (Examples 1-13), with values between 8-33 microns.
[0102] The values of the line thickness also demonstrates the
reduced bleed of the defined dispersants, where the better bleed
control has the K/W, K/Y and K/R line thickness values to be
approximately the same for all three values, compared with the
control and comparative examples that have greatly different values
for the K/Y and K/R compared with the K/W value.
* * * * *